ORIGINAL ARTICLE

Facile and novel route for preparation of nanostructuredpolyaniline (PANi) thin films

D. K. Bandgar • G. D. Khuspe • R. C. Pawar •

C. S. Lee • V. B. Patil

Received: 23 August 2012 / Accepted: 4 November 2012 / Published online: 25 November 2012

� The Author(s) 2012. This article is published with open access at Springerlink.com

Abstract Simple and inexpensive single step facile novel

chemical route for the preparation of polyaniline (PANi)

nanofibers has been reported. These PANi nanofibers are

characterized with X-ray diffraction (XRD), Fourier

transform infrared (FTIR) spectroscopy, Field emission

scanning electron microscopy (FESEM) and Transmission

electron microscopy (TEM). Polyaniline nanofibers exhibit

amorphous nature as confirmed from XRD and SAED

study. Based on FESEM and TEM analysis, the formation

of the polyaniline nanofibers with average diameter of

about 40 nm was inferred. The presence of characteristic

bonds of polyaniline was observed from FTIR spectros-

copy technique. Electrical and optical properties revealed

that p-type conductivity PANi with room temperature

conductivity of 2.77 9 10-5 (X cm)-1 has band gap of

3.40 eV. A blue shift of 0.86 eV with characteristic

absorption peak at 441 nm has been attributed due to

quantized size of polyaniline nanofibers.

Keywords Polyaniline � FESEM � FTIR � TEM � XRD

Introduction

Nanostructured materials today have immense importance

in the field of optoelectronics and biomedical. The exper-

imental and theoretical progress has opened new era of

fundamental physics and chemistry as researchers can

make and study artificial analogs of atoms, molecules and

crystals. Polymer materials have been widely used in

chemical reactions as supports or catalysts due to their

flexible applicability.

An attractive subject of research was initiated with the

discovery of conducting polymers (conjugated polymers).

Among the most commonly studied conducting polymers is

polyaniline, also known as highly tunable and air-stable

organic conducting polymer with good environmental sta-

bility, which can be produced as bulk powder, cast films or

fibers. This, in conjunction with the feasibility of low cost

monomer, large-scale production, redox reversibility serves

to further enhance its favorable properties and makes it an

ideal candidate in many applications. This could greatly

widen its applicability in multidisciplinary areas such as

electrical, electronics, thermoelectric, electrochemical,

electromagnetic, electromechanical, electro-luminescence,

electrorheological, chemical, membrane and sensors

(Borole et al. 2006; Jacinth Mispa et al. 2011; El Ghanem

et al. 2006; Pawar et al. 2009; Chougule et al. 2012a). The

PANi can mainly occur in three forms, including so-called

fully reduced pale yellow-colored leucoemeraldine (LEB),

the partially oxidized green-colored emeraldine base (EB)

and fully oxidized bluish-violet colored pernigraniline

(PEB). The electrical and optical properties of the poly-

aniline vary with the different oxidation states and different

forms. It can be configured or controlled to conduct across

a wide range, from being utterly non-conductive for insu-

lation use to highly conductive for other electrical purposes

(Patil et al. 2012). The emeraldine base is more stable form

in air at ambient temperature.

The available literature revealed different methods to

synthesize PANi including electrochemical (Patil et al.

2009), template (Raut et al. 2012a), enzymatic (Kobayashi

D. K. Bandgar � G. D. Khuspe � V. B. Patil (&)

Materials Research Laboratory, School of Physical Sciences,

Solapur University, Solapur 413255, MS, India

e-mail: drvbpatil@gmail.com

R. C. Pawar � C. S. Lee

Department of Materials Engineering,

Hanyang University, Ansan 426-791, South Korea

123

Appl Nanosci (2014) 4:27–36

DOI 10.1007/s13204-012-0175-8

et al. 2001), plasma (Nastase et al. 2005), photo (Kobay-

ashi et al. 1998), subdivision of chemical polymerization

into heterophase (Vidotto et al. 1969), solution (Kuramoto

and Tomita 1997), interfacial (Dallas et al. 2007), seeding

(Xing et al. 2006), metathesis (Zhang et al. 2009), self-

assembling (Bahgat et al. 2003) and sonochemical (Jing

et al. 2006) polymerizations.

The unnecessary formation of precipitation, waste of

material in many of the above reported methods that are

money, time and energy consuming, cumbersome along

with needed sophisticated instruments for controlling var-

ious parameters may put restrictions on the commercial

synthesis of materials. These can be avoided by facile and

novel in situ chemical route which results into entailed thin

film form of the deposit at room temperature.

Khuspe et al. reported microstructural and optical prop-

erties of nanostructured polyaniline in semiconducting form

PANi (EB) by chemical oxidation polymerization method

for ammonia gas sensing applications (Khuspe et al. 2012).

Following reasons strongly portrays our in situ chemical

route as facile, novel and efficient among the rest deposi-

tion methods. It is relatively simpler and cheaper method

that has emerged as one of the recent soft chemical solution

methods. It is advantageous due to layer-by-layer growth

and comprises excellent material utilization efficiency,

good control over deposition process along with film

thickness and specifically convenient for large area depo-

sition on virtually any type of substrate. The in situ prep-

aration of PANi film results in pinhole free and uniform

deposits, since the basic building blocks are ions instead of

atoms. Oxidation and corrosion of metallic substrates can

be avoided as deposition is carried at or near room tem-

perature (Chougule et al. 2011; Raut et al. 2012b).

In this work, a systematical investigation on the oxida-

tive chemical polymerization of aniline is made as simple

as possible by facile lucrative in situ chemical route at

room temperature, which results in good quality, uniform,

well-adherent, porous and nanofiberous-structured semi-

conducting polyaniline (PANi-EB) in the thin film form

feasible for large area deposition. Our efforts are focused

onto development of easiest and cheapest synthesis route

for the preparation of PANi (EB) commercially, so that to

achieve compatibility in applications. Further, in situ

grown films are characterized for study of structural,

morphological, optical and electrical transport properties.

Experimental details

Aniline monomer and other reagents, such as dopant HCl,

oxidant (ammonium peroxydisulfate, APS) were used as

received [AR grade, Sd. fine Chem. Ltd, Mumbai (India)].

A typical in situ polymerization technique was employed to

synthesize PANi thin films onto glass substrate (Fig. 1).

The polymerization procedure was as follows: PANi was

prepared by chemical oxidation process using aqueous

acidic solution of 0.2 M aniline (C6H5NH2) ? 0.1 M

APS ? 0.2 M HCl.

The reaction mixture was kept for 3 h at the room

temperature, briefly stirred and left at rest to polymerize for

5 h. The green precipitate occurred. The resultant product

was PANi in emeraldine salt form, i.e., PANi (ES). To

obtain emeraldine base form of PANi, dedope ES form of

PANi with 0.1 M NH4OH solution and pre-cleaned glass

substrates were dipped in the beaker. The solution was

briefly stirred and left at rest to polymerize at room tem-

perature. The blue thin layer of PANi deposited on the

glass substrate after 3 h; thus, finally obtained film of

insulating polyaniline (EB). The resulting PANi film was

washed under distilled water to remove the low molecular

weight organic intermediates, oligomers, etc. and dried at

the room temperature and used for further studies.

Thickness of deposited PANi thin film was measured

using fully computerized AMBIOS Make XP–1 surface

Fig. 1 The schematic of in situ

method for deposition of PANi

on the substrate

28 Appl Nanosci (2014) 4:27–36

123

profiler with 1 A vertical resolution and found to be

110 nm. The XRD pattern was taken under the conditions of

40 kV and 100 mA with CuKa radiations (K = 1.5426 A)

using Philips PW 3710, X-ray diffractometer (XRD) for

structural studies. The surface morphology and grain size of

the PANi nano fiber have been characterized by FESEM

(XL30 ESEMFEG) and transmission electron microscopy

(Philips CM-30 TEM unit, point resolution = 2.4 A) with

acceleration voltage of 300 kV coupled with EDAX-DX-4

analyzer. The AFM images were obtained using a scanning

probe microscope (SPM-Solver P47, NTMDT, Russia) in

contact mode. The FT-IR spectrum of the sample was col-

lected using a ‘Perkin Elmer, FT-IR Spectrum one’ unit.

UV–Vis absorption spectra were recorded on a Systronic

spectrophotometer-119 with glass substrate as a reference in

the wavelength range of 300–1,000 nm. The electrical

transport properties were studied using two probe techniques

in 300–500 K temperature range.

Results and discussion

Reaction mechanism

Chemical polymerization is a simple and fast process with

no need for special instruments. During the chemical

polymerization of aniline, electroneutrality of the polymer

matrix is maintained by incorporation of anions from the

reaction solution. These counter ions are usually the anions

of the chemical oxidant or reduced product of oxidant. In

present investigation ammonium persulfate (APS) is used

as chemical oxidant for chemical polymerization. The

possible reaction mechanism for in situ chemical poly-

merization of polyaniline is given as follows:

For preparation of semiconducting polyaniline (poly-

aniline base) by novel in situ chemical polymerization,

reaction mixture contains the solution of 0.2 M aniline

prepared in 1 M hydrochloric acid which serves as a cat-

ionic precursor at room temperature with pH & 1.

Ammonium persulfate in double distilled water acts as

oxidizing agent at room temperature. 0.1 M ammonium

persulfate solution in water (pH & 3) at room temperature

(as anionic precursor solution) was suddenly added into the

above solution. Here, anilinium cations are the prevailing

monomer species. Further reaction is followed by the

immersion of the glass substrate in the solution; intuitively

wherein, the oxidative chemical polymerization reaction

with monomer species of anilinium cations occurs. First,

oxidation of anilinium cation monomer species takes place

by persulfate anions. The two electron oxidation reaction of

anilinium cation by persulfate anion, leading to generation

of aniline nitrenium (C6H5NH?) cation is explained in

Scheme 1b (Trivedi 1997; Konyushenko et al. 2006). An

efficient polymerization of aniline is achieved in an acidic

media wherein, aniline exists as an anilinium cation

(C6H5NH3?) (Trivedi 1997). The anilinium chloride pro-

duced by the reaction of aniline and hydrochloric acid

(Khuspe et al. 2012; Konyushenko et al. 2006; Perrin 2003)

acts as a cation source and can be explained by the reaction

shown in Scheme 1a. When substrate is immersed in the

above solution, these anilinium cations get adsorbed on

the substrate due to the attractive force between surface of

the substrate and ions in the solution. These forces may be

cohesive forces or van der Waals forces or chemical

attractive forces. And second, adsorbed aniline nitrenium

cations (C6H5NH?) react with hydrochloride anions

(HCl-) leading into the formation of dark green-colored

PANi (emeraldine) hydrogen chloride as shown in Sche-

me 1c. Anilinium cation in the form of anilinium chloride

is produced after reaction of aniline with hydrochloric acid

and further oxidized with ammonium persulfate at room

temperature to produce PANi (emeraldine) hydrochloride

(Konyushenko et al. 2006). Protonated polyaniline (PANi

hydrochloride) when treated with ammonium hydroxide

converts to a semiconducting blue emeraldine base

(pH & 8) layer with only a few nanometer thickness as

shown in Scheme 1d.

Structural analysis

The crystallinity and orientation of conducting polymers

have been of much interest because highly ordered systems

can display metal-like conductive states (Li et al. 1993).

Figure 2 shows a typical XRD pattern for polyaniline thin

films on glass substrates. Figure 2 also displays broad

diffraction peak corresponding to 2h = 25.30� (110) which

is consistent with XRD patterns of the polyaniline observed

by other groups (Chaudhari and Kelkar 1996, 1997). The

peak at 2h = 25.30� may be ascribed to periodicity parallel

to the polymer chain (Moon et al. 1989). The peak at

2h = 25.30� may also represent the characteristic distance

between the ring planes of benzene rings in adjacent chains

or the close contact interchain distance (Pouget et al. 1995).

The characteristic broadening of the observed peaks

implies that the films are nanocrystalline.

Microstructural analysis

The two-dimensional surface morphology of the polyani-

line thin films has been studied using FESEM images.

Figure 3 shows the FESEM images of polyaniline thin

film. Polyaniline surface with fussy fibers is clearly seen

from FESEM images. FESEM image confirms the inter-

connected polyaniline nanofibers. The fibers are relatively

smooth with randomly distributed over the substrate and

these nanofibers are with approximately average diameter

Appl Nanosci (2014) 4:27–36 29

123

of 40 nm. The micrograph shows the interconnected

nanofibers forming web-like structure with hollow cavities

which are highly porous. The porous nature of the

polyaniline makes it a potential candidate for various

surface-related applications such as gas sensors and energy

storage devices.

The morphology of PANi (EB) consisting strongly

interconnected fibers was further studied with high mag-

nified TEM analysis (Fig. 4a). It shows that the film

composed of interconnected nanofibers of average diame-

ter around 40 nm, which is in consistent with grain size

calculated from FESEM studies.

Figure 4b shows corresponding selected area electron

diffraction (SAED) pattern of polyaniline nanofibers. The

blurred bright electron diffraction rings show that the

polyaniline film is amorphous or poorly crystalline, sup-

ported to X-ray diffraction results (Fig. 2).

The two- (2D) and three- (3D) dimensional surface topol-

ogy of the PANi thin films were investigated using atomic

force microscopy (AFM). Figure 5a, b shows the 2D and 3D

AFM micrographs of PANi thin films, respectively. From the

micrograph (5a), total coverage of the substrate with inter-

connected fibers is seen. From the 3D micrograph (Fig. 5b), it

is seen that the film consists of distributed cuboidal shaped

interconnected fibers with some visible voids, which is con-

sistent with FESEM image.

NH2 HCl NH3Cl

NH3 NH

NH3 2HCl NH

NH4S2O82e- oxidation 2HCl

Aniline Acid

Anilinium cation Anilinium nitrenium cation

4n NH NH NH

nHCl HCl

N NH NHN

n

Polyaniline (EB)

-2 n H+Cl-

deprotonation

Polyaniline (ES)

(c)

(b)

(a)

(d)

Anilinium cation(Aniliium Chloride)

Scheme 1 Reaction mechanism for in situ chemically deposited

PANi. a The reaction of aniline with hydrochloric acid gives

anilinium cations in the form of anilinium chloride. b The oxidative

chemical reaction of anilinium cations by persulfate anions of

ammonium persulfate leading to generation of aniline nitrenium

cations. c The next to oxidative chemical reaction, aniline nitrenium

cations react with hydrogen chloride anions to form PANi (emeral-

dine) salt and d polyaniline (emeraldine) salt is deprotonated in the

alkaline medium to polyaniline(emeraldine) base

10 20 30 40 50 60 70

(110

)

PANi

Inte

nsi

ty (

a.u

)

2θ (degrees)

Fig. 2 X-ray diffraction patterns of PANi (EB) film

30 Appl Nanosci (2014) 4:27–36

123

FTIR analysis

The FT-IR spectrum of the PANi in the range

500–4,000 cm-1 is shown in Fig. 6. Primly nine absorption

peaks are observed. The broad band at 3,428 cm-1 was

assigned to the free N–H stretching vibrations of secondary

amines (Zeng and Ko 1998; Trchova et al. 2006). The smaller

one peak at 2,921 cm-1 is characterized to the vibration

associated with the NH2? part in the –C6H4NH2?C6H4–

group (Palaniappan and Narayana 1994; Quillard et al. 2001).

The band at 1,559 cm-1 is due to quinoid ring deformations

of aromatic ring. The peaks at 1,470 and 1,292 cm-1 are

the results of the stretching vibrations of C N? and C–N,

respectively (Kang et al. 1998). The peaks at 1,121 and

801 cm-1 are attributed to the aromatic C–H bending in the

plane and out of the plane for the 1, 4-disubstituted aromatic

ring (Colak and Sokmen 2000; Liu et al. 2002). The band at

499 cm-1 is attributed to S–C stretching vibration mode,

indicating the presence of the chloro group which supports

formation of emeraldine PANi hydrogen chloride. Chloronate

groups interact with protonated imine nitrogen in neighboring

chains and stabilize the PANi. All the above observed

absorption characteristics confirm the formation of PANi.

Electrical transport properties

DC electrical conductivity

The dc electrical conductivity of polyaniline film was

measured in the 300–500 K temperature range and their

temperature dependence can be fitted to a usual Arrhenius

equation:

r ¼ roexp �Ear=KTð Þ ð1Þ

where, r is the conductivity at temperature T, ro is a

constant, k is the Boltzmann constant, T is the absolute

temperature and Ea is the activation energy. The activation

energy represents the location of trap levels below the

conduction band. The temperature dependence of dc elec-

trical conductivity of PANi (EB) (Fig. 7) showed two

distinct conduction regions corresponding to two different

conduction mechanisms; one, a grain boundary scattering

limited and second a variable range hopping (Raut et al.

2012b; Patil et al. 2011). From Fig. 7, it is observed that

conductivity obeys Arrhenius behavior indicating aFig. 3 FESEM micrograph of PANi (EB) thin film

Fig. 4 a TEM image of polyaniline nanofibers, b SAED pattern of corresponding polyaniline nanofibers

Appl Nanosci (2014) 4:27–36 31

123

semiconducting transport behavior. The activation energies

of an electrical conduction have been computed for both

high and low temperature regions (from Fig. 7) and are

0.66 and 0.24 eV, respectively.

Thermo-emf measurement

The temperature difference causes a transport of carriers

from the hot to cold end and thus creates an electric field,

which gives rise to a thermally generated voltage. The

thermo-emf property of polyaniline was measured as a

function of temperature in the 300–500 K temperature

range and is shown in Fig. 8.

The thermo-emf developed between two ends showed

that the polyaniline is a p-type electrical conductivity

material and that the holes contribute to TEP similar to the

results reported earlier (Chougule et al. 2012b). The

thermo-emf increased linearly with increasing temperature.

Chougule et al. (2012c) have also reported that the ther-

moelectric power increases with increase in temperature

for organo-soluble polyaniline doped with HCl. The TEP

results indicate that the conductivity mechanism of the

polymer is controlled by the large polaron hopping model.

From the experimental observations it appeared that the

temperature dependence of thermo power is approximately

linear in the low temperature region whereas it deviated

from the linear behavior at higher temperature and obeys

power law dependence of the temperature. The non-line-

arity of the plots indicates non-degeneracy of the material

whose thermoelectric power is proportional to nth power of

Fig. 5 The 2D a and 3D b AFM images of polyaniline thin film

500 1000 1500 2000 2500 3000 3500 4000

4.0

4.5

5.0

5.5

6.0

6.5

7.0

499

801

1121 12

92

1470 15

59

2316

2921 34

28

PANi(EB)

T %

Wavelength (cm-1)

Fig. 6 FTIR spectra of PANi (EB) thin film

1.8 2.0 2.2 2.4 2.6 2.8 3.0

0.0

2.0x10-3

4.0x10-3

6.0x10-3

8.0x10-3

1.0x10-2

1.2x10-2

PANi(EB)σ

Ω

1000/T, K

Co

nd

uct

ivit

y,

( c

m)-1

Fig. 7 Plot of dc electrical conductivity (r) versus inverse temper-

ature of PANi (EB) film

32 Appl Nanosci (2014) 4:27–36

123

the absolute temperature. For such semiconductors ther-

moelectric power is a weak function of the temperature and

can be represented as (Sekkina and Tawfik 1995):

P ¼ �K=e½r þ 5=2� þ ln f2ð2p md�kTÞ3=2=nhg3 ð2Þ

where P is thermoelectric power in mVK-1, A = r ? 5/2

is a thermoelectric factor that depends on the various

scattering mechanisms, md* is the density of states

effective mass and n is the carrier concentration.

Equation (2) can be solved for appropriate values of A

and md*, and carrier concentration (n) were calculated for

all the samples at different temperatures. The charge carrier

motilities (l) were determined using the standard relation.

l ¼ r=n � e ð3Þ

Figure 9 is a plot of the carrier concentration (n) and

mobility (l) as a function inverse absolute temperature. It

is seen that the carrier concentration and mobility are

dependent functions of the temperature. These variations

are analogous with that of the electrical conductivity

variations. The observed value of n and l is of the order of

1019 cm-3 and 10-6 cm2 V-1 s-1. Further, the mobility

increased with the applied temperature suggesting the

presence of scattering mechanism associated with the inter

grain barrier height as proposed by Petriz (1956).

The temperature-dependent grain boundary mobility is

related to the grain boundary poetical as (Micocci et al.

1995):

l ¼ l0 exp �Ub=kTð Þ ð4Þ

where Ub is the inter grain barrier potential and l0 is the

pre exponential factor. The inter grain barrier potential is

therefore determined from the variation of the log lT1/2

versus 1/T as suggested by Micocci et al. (1963). This is

shown in Fig. 10 and its typical value is 0.49 eV.

From the observed values of the activation energies of

an electrical conduction (Ear) and the electron density

(Ean), the relation

Ear ¼ Ean þ Ub ð5Þ

holds good. This is expected from the interrelationship

between the electrical conductivity, carrier density and

mobility (Patil et al. 2011; Raut et al. 2012c; Sekkina and

Tawfik 1995; Petriz 1956; Micocci et al. 1995).

Thermo-gravimetric analysis (TGA) and differential

thermal analysis (DTA)

Thermo gravimetric analysis and DTA of polyaniline in

powder form were carried out to study endothermic and

300 350 400 450 5000.0

0.5

1.0

1.5

2.0

Th

erm

o-e

mf

(mV

)

Temperature,(oK)

PANi(EB)

Fig. 8 Variation of thermo-emf with temperature of polyaniline thin

film

2.0 2.2 2.4 2.6 2.8 3.0 3.2-1.2

-1.6

-2.0

-2.4

-2.8PANi(EB)

(b)

(a)

(a) mobility (b) carrier density

1000/T, K-1

μ

19.2

19.3

19.4

log

n (

cm

log

(c

m2 ,

V-1

s-1)

-3)

Fig. 9 Plot of log n and log l as a function of inverse temperature

for PANi thin film

2.0 2.2 2.4 2.6 2.8 3.0 3.2

-4

-5

-6

-7

PANi(EB)

log

μT

1/2

1000/T, K-1

Fig. 10 Determination of intercrystalline barrier height for PANi

film

Appl Nanosci (2014) 4:27–36 33

123

exothermic reactions at a heating rate of 10 K/min in air

atmosphere from 273 to 1,273 K as shown in Fig. 11.

The thermal evolution in air atmosphere takes place in

four consecutive stages corresponding to weight losses in

which the inflection point coincides with the temperature of

the endotherms and exotherms in DTA trace. The weight

loss of polyaniline begins at 323 K. The weight loss

commencing at around 373 K is assigned to the loss of

initially present water molecules (Duval 1963). Rapid

weight loss is found in temperature range of 493–743 K

due to the consequence of structural decomposition of the

polymer and elimination of dopant molecules. After 743 K,

the DTA trace is stable with no further weight loss is

observed. This indicates that the polyaniline is stable up to

323 K and then polyaniline starts degrading slowly. The

smooth thermogram shows only one exothermic peak at

668 K, where thermal decomposition of polyaniline takes

place. Ansari and Keivani (2006) obtained the similar

behavior of polyaniline prepared by cyclic voltammetry

and reported that the polyaniline prepared by cyclic vol-

tammetry is highly thermal stable than that of prepared by

potentiostatic mode.

Optical absorption studies

Figure 12 shows the variation of optical absorbance (at)

with incident photon wavelength (k) of the polyaniline thin

film having thickness of 110 nm. The UV–Vis–NIR

absorption spectrum of PANi film shows two sharp

absorptions: one with maximum at 441 nm (&3.4 eV)

p–p* transition of benzenoid ring and another at 652 nm

(&2.04 eV) corresponding to molecular exciton transition.

This is due to the oxidation states of the PANi (de Albu-

querque et al. 2004).

As seen in figure, peak generally preferred to as the

excitonic peak, which is the typical characteristic of

nanocrystallites, follows the absorption at 425–450 nm.

The absorbance band approximately at 440 nm has been

reported earlier and may be attributed to the excitation to

the polaron band (Wang and Herron 1991). For semicon-

ductor materials, the quantum size effect is expected if the

semiconductor dimension becomes smaller than the Bohr

radius of the exciton and the absorption edge is red shifted.

The theory of optical absorption gives the relationship

between the absorption coefficient (a) and the photon

energy (ht) for direct allowed transition can be written as:

aht ¼ a0 ðht � EgÞ1=2 ð6Þ

where a0 is a constant, ht is the photon energy and Eg is the

band gap of the material. Inset of Fig. 12 shows the vari-

ation of (aht)2 with incident photon energy (ht), the band

gap, Eg, was determined. The band gap was found to be

3.40 eV which is lower than earlier reported by Sajeev

et al. (2006) (3.65 eV) and higher than earlier reported by

Pawar et al. (2011) (2.54 eV), showing a blue shift of

0.86 eV. This is attributed to the size quantization of

nanofibered polyaniline thin films. It is well known that the

band gap energies for the well-crystallized thin films are

comparable to those of crystallized bulk materials, where

as in amorphous and/or nanocrystallized forms, the band

gap energies are higher than those of the corresponding

bulk materials.

Conclusion

In conclusions, a direct one-step and environmentally

friendly simple, inexpensive facile and novel chemical

synthesis method has been developed to produce fussy

polyaniline nanofibers at room temperature.

This may be helpful for commercially synthesis of

polyaniline. Study of physico-chemical characteristics with

Fig. 11 TGA–DTA spectra of polyaniline thin film in air

atmosphereFig. 12 The plot of absorption (at) with wavelength (k) of PANi thin

film on glass substrate

34 Appl Nanosci (2014) 4:27–36

123

XRD, FT-IR, FESEM, TEM, SAED, AFM, optical and

electrical techniques confirmed preparation of amorphous,

nanostructure, wide optical band gap and low resistivity of

p-type PANi thin film. The in situ chemical method is

efficient and constructive for deposition of fused nanofibers

like PANi films onto substrates of different area with fea-

sibility, at expense of small amount of initial ingredients.

Acknowledgments Authors (VBP) are grateful to DAE-BRNS, for

financial support through the Scheme No. 2010/37P/45/BRNS/1442.

Open Access This article is distributed under the terms of the

Creative Commons Attribution License which permits any use, dis-

tribution, and reproduction in any medium, provided the original

author(s) and the source are credited.

References

Ansari RM, Keivani EB (2006) Polyaniline conducting electroactive

polymers: thermal and environmental stability studies. J Chem

3:202–217

Bahgat AA, Sayyah SM, Abd-Elsalam HM (2003) Study of

ferroelectricity in polyaniline. Int J Polym Mater 52:499–515

Borole DD, Kapadi UR, Mahulikar PP, Hundiwale DG (2006)

Synthesis of nano polyaniline and poly-o-anisidine and applica-

tions in alkyd paint formulation to enhance the corrosion

resistivity of mild steel. Polym Plast Technol Eng 45:667

Chaudhari HK, Kelkar DS (1996) X-ray diffraction study of doped

polyaniline. J Appl Polym Sci 62:15–18

Chaudhari HK, Kelkar DS (1997) Investigation of structure and electrical

conductivity in doped polyaniline. Polym Int 42:380–384

Chougule MA, Pawar SG, Patil SL, Raut BT, Patil VB (2011)

Polypyrrole thin films: room temperature ammonia sensor. IEEE

Sensor J 11:2137–2141

Chougule MA, Patil SL, Pawar SG, Raut BT, Godse PR, Sen S, Patil

VB (2012a) Facile and efficient route for preparation of

Polypyrrole–ZnO nanocomposites: microstructural optical and

charge transport properties. J Appl Polym Sci. doi:10.1002/

app36475

Chougule MA, Sen S, Patil VB (2012b) Polypyrrole-ZnO hybrid

sensor: effect of camphor sulfonic acid doping on physical and

gas sensing properties. Synth Metals 162:1598–1603

Chougule MA, Sen S, Patil VB (2012c) Polypyrrole–ZnO nanohy-

brids: effect of CSA doping on structure, morphology and

optoelectronic properties. J Appl Nanosci. doi:10.10060/s13204-

012-0149-x

Colak N, Sokmen B (2000) Doping of chemically synthesized

polyaniline. Des Monomers Polym 3:181–189

Dallas P, Stamopoulos D, Boukos N, Tzitzios V, Niarchos D, Petridis

D (2007) Characterization, magnetic and transport properties of

polyaniline synthesized through interfacial polymerization.

Polymer 48:3162–3169

de Albuquerque JE, Mattoso LHC, Faria RM, Masters JG, MacDi-

armid AG (2004) Study of the interconversion of polyaniline

oxidation states by optical absorption spectroscopy. Synth Met

146:1–10

Duval C (1963) Inorganic thermogravimetric analysis. Elsevier,

Amsterdam, p 315

El Ghanem HM, Attar H, Sayid Ahmad H, Abduljawad S (2006)

Dielectric spectroscopy of conducting polyaniline polymer. Int J

Polym Mater 55:663–679

Jacinth Mispa K, Subramaniam P, Murugesan R (2011) Oxidative

polymerization of aniline using zirconium vanadate, a novel

polyaniline hybrid ion exchanger. Des Monomers Polym 14:

423–432

Jing XL, Wang YY, Wu D, She L, Guo Y (2006) Polyaniline

nanofibers synthesized by rapid mixing polymerization. J Polym

Sci Polym Chem 44:1014

Kang ET, Neoh KG, Tan KL (1998) Polyaniline: a polymer with many

interesting intrinsic redox states. Prog Polym Sci 23:277–324

Khuspe GD, Bandgar DK, Patil VB (2012) Fussy nanofibrous

network of polyaniline (PANi) for NH3 detection. Synth Metals

162:1822–1827

Kobayashi N, Teshima K, Hirohashi R (1998) Conducting polymer

image formation with photoinduced electron transfer reaction.

J Mater Chem 8:497–506

Kobayashi S, Uyama H, Kimura S (2001) Synthesis and chemical

properties of polyphenols with oligoaniline pendant groups.

Chem Rev 101:3793

Konyushenko EN, Stejskal J, Sedenkov I, Trchov M, Sapurina I,

Cieslar M, Prokes J (2006) Evolution, performance, ageing and

reincarnation of polyaniline. Polym Int 55:31

Kuramoto N, Tomita A (1997) Chemical oxidative polymerization of

dodecylbenzenesulfonic acid aniline salt in chloroform. Synth

Met 88:147–151

Li Q, Cruz L, Philips P (1993) Low-temperature heat capacities of

polyaniline and polyaniline polymethylmethacrylate blends.

Phys Rev B 47:1840

Liu H, Hu XB, Wang JY, Boughton RI (2002) Structure, conductiv-

ity, and thermo power of crystalline polyaniline synthesized by

the ultrasonic irradiation polymerization method. Macromole-

cules 35:9414–9419

Micocci G, Tepore A, Rella R, Siciliano P (1995) Electrical and

optical characterization of electron beam evaporated In2Se3 thin

films. Phys Status Solidi A 148:343–431

Moon YB, Cao Y, Smith P, Heeger AJ (1989) Composite films of

nanostructured polyaniline with poly(vinyl alcohol). Polym

Commun 30:196

Nastase C, Nastase F, Dumitru A, Ionescu M, Stamatin I (2005) Thin

film composites of nanocarbons-polyaniline obtained by plasma

polymerization technique. Compos A Appl Sci Manuf 36:481–485

Palaniappan S, Narayana BH (1994) Composition and spectral studies

of polyaniline salts. Polym Adv Technol 5:225–230

Patil VB, Pawar SG, Patil SL, Sood AK (2009) Optoelectronic and

microstructural properties of PANi (EB)-CSAX polymer thin films

by novel spin coating method. Orient J Chem 25(4):945–952

Patil SL, Pawar SG, Chougule MA, Sen S, Patil VB (2011)

Nanocrystalline ZnO thin films: Effect of annealing on micro-

structural and optoelectronic properties. J Alloys Compd 509:

10055–10061

Patil SL, Pawar SG, Chougule MA, Raut BT, Godse PR, Sen S, Patil

VB (2012) Structural, morphological, optical and electrical

properties of PANi–ZnO nanocomposites. Int J Polym Mater

61:809–820

Pawar SG, Patil SL, Mane AT, Raut BT, Patil VB (2009) Growth,

characterization and gas sensing properties of polyaniline thin

films. Arch Appl Sci Res 1(2):109–114

Pawar SG, Patil SL, Chougule MA, Achary SN, Patil VB (2011)

Microstructural and optoelectronic studies on polyaniline: TiO2

nanocomposite. Inter J Polym Mater 60:244–254

Perrin DD (2003) CRC Handbook of Chemistry and Physics, vol

1250, 84th edn. CRC Press, Boca Raton, p 1221

Petriz RL (1956) Theory of photoconductivity in semiconductor

films. Phys Rev 104:1508

Pouget JP, Hsu CH, Macdiarmid AG, Epstien AJ (1995) Synthesis of

iodine-capped aniline trimers and analysis of their electronic

spectrum. Synth Met 69:119

Appl Nanosci (2014) 4:27–36 35

123

Quillard S, Corraze B, Boyer MI, Fayad E, Louarn G, Froyer G

(2001) Vibrational characterization of crystallized oligianiline: a

model compound of polyaniline. J Mol Struct 596:33–40

Raut BT, Godse PR, Pawar SG, Chougule MA, Patil VB (2012a) New

method for fabrication of polyaniline–CdS sensor for H2S gas

detection. Measurements 45:94–100

Raut BT, Godse PR, Pawar SG, Chougule MA, Sen S, Pawar RC, Lee

CS, Patil VB (2012b) Novel method of fabrication of polyan-

iline–CdS nanocomposites: structural, morphological and opto-

electronic properties. Ceramic Inter J 38:3999–4007

Raut BT, Godse PR, Pawar SG, Chougule MA, Bandgar DK, Sen S,

Patil VB (2012c) New process for fabrication of polyaniline–

CdS nanocomposites: structural, morphological and optoelec-

tronic investigations. J Phys Chem Solids. doi:10.1016/j.jpcs.

2012.09.012

Sajeev US, Mathai CJ, Saravanan S, Ashokan RR, Venkatachalam S,

Anantharaman MR (2006) On the optical and electrical proper-

ties of rf and a.c. plasma polymerized aniline thin films. Bull

Mater Sci 29:159–163

Sekkina A, Tawfik A (1995) Further studies on the temperature

dependence of the electric and photovoltaic properties of CdSe

thin films for solar cells. Thermochim Acta 86:431–435

Trchova M, Sedenkova I, Konyushenko EN, Stejskal J, Holler P,

Ciric-Marjanovic G (2006) Polyaniline: the infrared spectros-

copy of conducting polymer nanotubes. J Phys Chem B 110:

9461–9468

Trivedi DC (1997) In: Nalwa HS (ed) Handbook of organic

conductive molecules and polymers, vol 2, issue no 2. Wiley,

Chichester, p 505

Vidotto G, Crosato-Arnaldi A, Talamini G (1969) Polymerization of

acrylonitrile in the presence of different solvents. Makromol

Chem 122:91–104

Wang Y, Herron N (1991) Nanometer-sized semiconductor clusters:

materials synthesis, quantum size effects and photophysical

properties. J Phys Chem 95:525–532

Xing S, Zhao C, Jing S, Wang Z (2006) Morphology and conductivity

of polyaniline nanofibers prepared by ‘seeding’ polymerization.

Polymer 47:2305–2313

Zeng XR, Ko TM (1998) Structure and properties of chemically

reduced polyaniline. Polymer 39:1187–1195

Zhang Y, Xu W, Yao W, Yu S (2009) Oxidation–reduction reaction

driven approach for hydrothermal synthesis of polyaniline

hollow spheres with controllable size and shell thickness.

J Phys Chem C 113(20):8588–8594

36 Appl Nanosci (2014) 4:27–36

123